Matched Filter Mean Acquisition Time Performance For P(Y), BOC(10,5), and MAN(10) Codes With FFT Aiding and Noncoherent Combining

J. K. Holmes and P. A. Dafesh

Abstract:	Over the years, a number of analyses of passive acquisition implementations of the passive matched filter (PMF) [1–4] code searches have been published. These implementations apply to acquisition of the GPS precision (P)-code, and the course acquisition (C/A) code signals as well as the new modernized GPS M code signal. While many receiver search schemes employ an active parallel search implementation, there has been recent interest in PMF search implementations due to their presumed fast search rates. This work studies the theoretical performance of a noncoherent PMF that utilizes a Fast Fourier Transform (FFT) frequency search along with noncoherent combining to enhance the performance in the face of interference. The P(Y) code, the binary offset carrier (BOC) code, and the intermodulation code (a Manchester code) are addressed in this analysis. The latter two codes will be discussed in some detail later in this paper. Due to the autocorrelation sidelobe levels of both the BOC and Manchester codes, both are acquired as dual NRZ codes that are offset ± 10.23 MHz from the carrier frequency by a 10.23 MHz squarewave subcarrier. This approach eliminates the problem of determining the maximum autocorrelation peak corresponding to the true code timing in acquisition and it is transferred to a tracking problem [5]. The performance of the PMF search is computed as a function of interferer-to-signal-power ratio under the assumption that a parallel frequency search using a zero padded (ZP) FFT, for flat interferer noise, matched spectral interference noise and a narrow band interferer. The P(Y) code, the BOC(10,5) (M code) and the Manchester(10) intermodulation code are analyzed in this paper, but the technique is applicable to other codes.
Published in:	Proceedings of the 57th Annual Meeting of The Institute of Navigation (2001) June 11 - 13, 2001 Albuquerque, NM
Pages:	121 - 139
Cite this article:	Holmes, J. K., Dafesh, P. A., "Matched Filter Mean Acquisition Time Performance For P(Y), BOC(10,5), and MAN(10) Codes With FFT Aiding and Noncoherent Combining," Proceedings of the 57th Annual Meeting of The Institute of Navigation (2001), Albuquerque, NM, June 2001, pp. 121-139.
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